Aluminum alloy



Patented Jan. 13, 1931 UNITED STATES, PATENT OFFICE gUGEN STRASSER, OFROIRSCHACH. SWITZERLAND, ASSIGNOR TO MAX DIETIK EBI, OF

. ZURICH, SWITZERLAND ALUMINUM ALLOY Io Drawing. Application filedFebruary 24, 1927, Serial No. 170,748, and in Germany February 27, 1926.

This invention has reference to aluminum alloys and particularly toalloys of the kind referred to which are adapted for casting purposes,and it is the object of this invention'toproduce an aluminum alloy whichis particularly distinguished by great strength, high tensileproperties, Brinellhardness and resistance to heat combined with a highdegree of density and superior working properties. The composition ofthe alloy accordin to this invention is such that the alloy will earconsiderable additions of zinc without thereby detracting from itsvaluable mechanical properties, so that by this addition the cost ofmanufacture may be considerably reduced.

In accordance with this invention I proceed by adding to the aluminum,the aluminum-zinc or to any other aluminum alloy diflicultly meltingmetals, and particularly such as are adapted to increase the tenacityand viscosity of the final product, these additions being made in theform of a preliminary alloy and preferably in such a manner that thispreliminary alloy may be deoxidized by the covering up of the layer ofliq uid' metal by a layer of salts suitable for forming a slagwith themetal oxides and becoming dissolved to a large extent by the action ofthe metal, and by the subsequent addition of a deoxidizing agent.

-In order to produce the valuable properties of the alloy it is forinstance suflicient.

to add as much as two percent only of the preliminary alloy which may becomposed in a preferred embodiment of copper, nickel and magnesium to aquantity of 98% aluminum and zinc. A very satisfactory alloy'of thiskind is composed of 98% aluminum and zinc, 1.8% copper, 0.1% nickel and0.1% magnesium. As a protecting salt-layer potassium-fiuoride may beused inthe manufacture of the preliminary alloy, and preferably about 3%of the total amount of the preliminary alloy. The manufacture of thealloy may for instance be carried out substantially as follows As thefirststep a preliminary alloy is obtained by melting copper and 5%nickel and sprinkling thereupon about 3%fluoride of potassium, KF, afterfusion. The potassorbed by the fused'metal. Afterthe salt has beencompletely liquefied 5% magnesium are added. The magnesium acts at thesame timeas a deoxidizing agent, and the portion not consumed thereby,constitutes an ingredient of the alloy. The oxide of magnesium which hasbeen produced by mutual reaction with the oxide originally present inthe metallicmass either in solution or in 'the colloidal state, forms aslag with the salt and rises with it to the surface, where it continuesto form a slag with the cover of salt. The fused metal is thereby freedfrom oxides in a manner and to an extent heretofore not known. 2% of thepreliminary alloy thus obtained are then added to a supply of 98%aluminum and zinc. As the result an alloy is obtained consisting of 98%aluminum and zinc, 1.8% copper, 0.1% nickel and 0.1%

magnesium. In this alloy up to 18% of zinc and even more zinc may becontained, inasmuch as this ingredient has a favorable in fiuence on themechanical qualities of the casting to be obtained. I

In order to' full utilize the good qualities of this alloy it is oimportance to arrange for a chilling action in the casting of the piecesof casting, and this. chilling should avoid excesses in eitherdirection, so as not to be too strong and not too low, but a kind ofmedium degree of chilling should be obtained, as occursfor instance inthe employment of a mould comprising moulding sand with an admixture ofmetal in powdered or' granular condition and containing about 6% ofwater when being used for casting pur poses. A similar action may beproduced by means of a dry'mould consisting of-a mass of mouldingmaterial containing for instance clayor mixtures of loam, calfs hairs,chopped straw and the like, if this mould after drying is likewisemoistened with about 6% of water; also with this dry mould it is ofimportance that in the manufacture of the moulding mass an admixture ismade of metal In case the chilling action has been too high as a resultof excessive moisture in the mould the piece of casting may be improvedby tempering it for several hours at a tem- 5 perature above themetallurgical point of con- 7 version which is specific to the alloyunder" treatment, and by then submitting it to a retarded or prolongedcooling action. In the subsequent aging of the casting a very con- 10siderable acceleration will be found in the attainment of the mostfavorable values for the mechanical properties. I wish it to'beunderstood that the mode of procedure and kind and percentages of in-'gredients herein enumerated are merely stated by Way of exemplificationand illustration of the principles of the invention without excludingmodifications and changes thereof, except as otherwise contained andstated in V the appended claim.

j Iclaim:

A method of manufacturing an aluminum alloy casting, consisting inmaking a preliminary alloy ofapproximately 90% copper and 5% nickel,covering the same with a fused layer of potassium-fluoride adaptedtoscorify the metal oxides present, adding approximately 5% of magnesiumwhile stirrin and then casting the preliminary alloy; a ding about 2 percent of this preliminary alloy to aluminum or aluminum-zinc alloycontaining up to 18% zinc, casting the same in a mold consisting of amaterial having a chilling effeet on the alloy, said mold materialcontaining granulated metal and having a water content of about 6%; theaging of the resulting alloy thus taking place during the progress ofthe process without the necessity of subsequent heattreatment. Y 0 Intestimony whereof I afix my signature.

' EUGEN STRASSER.

